Preparation of a composition comprising an alkaline earth metal oxide and a substrate having a reduced amount of grit

Abstract

The present invention relates to a composition comprising an alkaline earth metal carbonate and a substrate, where the composition has a reduced amount of grit, such as an amount less than or equal to about 0.5% by weight relative to the total weight of the composition. The composition can be a filler composition for use in, for example, paper making applications. Where the alkaline earth metal is a calcium carbonate, the grit can be reduced by degritting a slaked lime slurry prior to precipitation of the alkaline earth metal with the substrate. The degritting can be performed by hydrocycloning the lime slurry. The invention also relates to a method of coprecipitating calcium carbonate onto a substrate, and to a method of reducing grit in such compositions. The invention also relates to uses of these compositions, such as in paper-making applications, and to systems for producing these compositions.

1 . A filler composition, comprising: 
 at least one substrate; and    at least one alkaline earth metal carbonate precipitated on the substrate;    wherein the filler composition contains grit in an amount less than or equal to about 0.5% by weight relative to the total weight of the filler composition.    
     
     
         2 . The composition according to  claim 1 , wherein the composition contains grit in an amount less than or equal to about 0.2% by weight relative to the total weight of the composition.  
     
     
         3 . The composition according to  claim 2 , wherein the composition contains grit in an amount less than or equal to about 0.1% by weight relative to the total weight of the composition.  
     
     
         4 . The composition according to  claim 3 , wherein the composition contains grit in an amount less than or equal to about 0.05% by weight relative to the total weight of the composition.  
     
     
         5 . The composition according to  claim 4 , wherein the composition contains grit in an amount less than or equal to about 0.01% by weight relative to the total weight of the composition.  
     
     
         6 . The composition according to  claim 1 , wherein the grit has a diameter of at least about 35 μm and is present in the composition in an amount of less than or equal to about 0.5% by weight relative to the total weight of the composition.  
     
     
         7 . The composition according to  claim 6 , wherein the grit has a diameter of at least about 45 μm.  
     
     
         8 . The composition according to  claim 7 , wherein the grit has a diameter of at least about 50 μm.  
     
     
         9 . The composition according to  claim 1 , wherein the at least one substrate is chosen from particulate materials and fibrous materials.  
     
     
         10 . The composition according to  claim 1 , wherein a source of the at least one substrate is a fiber-containing stream.  
     
     
         11 . The composition according to  claim 1 , wherein a source of the at least one substrate is a fines-containing stream.  
     
     
         12 . The composition according to  claim 1 , wherein a source of the at least one substrate is whitewater.  
     
     
         13 . The composition according to  claim 1 , wherein a source of the at least one substrate is a fiber-containing stream comprising fibers derived from broke.  
     
     
         14 . The composition according:to  claim 1 , wherein a source of the at least one substrate is a fiber-containing stream comprising fibers derived from paper.  
     
     
         15 . The composition according to  claim 1 , wherein a source of the at least one substrate is an effluent stream.  
     
     
         16 . The composition according to  claim 15 , wherein the effluent stream is from a paper making plant.  
     
     
         17 . The composition according to  claim 1 , wherein the at least one substrate comprises a white mineral.  
     
     
         18 . The composition according to  claim 1 , wherein the at least one substrate comprises calcium carbonate.  
     
     
         19 . The composition according to  claim 1 , wherein the at least one substrate comprises precipitated calcium carbonate.  
     
     
         20 . The composition according to  claim 1 , wherein the at least one substrate comprises kaolin.  
     
     
         21 . The composition according to  claim 1 , wherein the at least one substrate comprises TiO 2 .  
     
     
         22 . The composition according to  claim 1 , wherein the at least one substrate comprises talc.  
     
     
         23 . The composition according to  claim 1 , wherein the at least one alkaline earth metal carbonate is a precipitated alkaline earth metal carbonate.  
     
     
         24 . The composition according to  claim 1 , wherein the at least one alkaline earth metal carbonate is calcium carbonate.  
     
     
         25 . The composition according to  claim 1 , wherein the at least one alkaline earth metal carbonate is magnesium carbonate.  
     
     
         26 . The composition according to  claim 1 , wherein the at least one substrate comprises at least one particulate material having a mean diameter less than or equal to about 300 μm.  
     
     
         27 . The composition according to  claim 26 , wherein the at least one substrate comprises at least one particulate material having a mean diameter less than or equal to about 250 μm.  
     
     
         28 . The composition according to  claim 27 , wherein the at least one substrate comprises at least one particulate material having a mean diameter less than or equal to about 150 μm.  
     
     
         29 . The composition according to  claim 27 , wherein the at least one substrate comprises at least one particulate material having a mean diameter less than or equal to about 75 μm.  
     
     
         30 . The composition according to  claim 1 , wherein the at least one substrate comprises at least one fibrous material having a mean length of less than or equal to about 75 μm.  
     
     
         31 . The composition according to  claim 1 , wherein the at least one substrate passes through a round hole having a diameter of about 76 μm.  
     
     
         32 . The composition according to  claim 1 , wherein the at least one substrate passes through a 50 mesh screen.  
     
     
         33 . The composition according to  claim 32 , wherein the at least one substrate passes through a 100 mesh screen.  
     
     
         34 . A paper comprising the composition according to  claim 1 .  
     
     
         35 . The paper according to  claim 34 , wherein the paper further comprises at least one ingredient chosen from ground calcium carbonate, kaolin, metakaolin, talc, and calcium sulphate.  
     
     
         36 . A polymer comprising the composition according to  claim 1 .  
     
     
         37 . A method of precipitating calcium carbonate comprising: 
 (a) providing a slaked lime slurry;    (b) degritting the slaked lime slurry;    (c) combining the degritted slaked lime with at least one substrate; and    (d) precipitating the degritted slaked lime in (c) as calcium carbonate in the presence of the at least one substrate.    
     
     
         38 . The method according to  claim 37 , wherein the degritted slaked lime in (c) is precipitated as calcium carbonate onto the at least one substrate.  
     
     
         39 . The method according to  claim 37 , wherein the at least one substrate is chosen from particulate materials and fibrous materials.  
     
     
         40 . The method according to  claim 37 , wherein the slurry in (a) comprises calcium hydroxide in an amount ranging from about 0.5 mol to about 3.0 mol per liter.  
     
     
         41 . The method according to  claim 37 , wherein the slaked lime is screened prior to degritting.  
     
     
         42 . The method according to  claim 37 , wherein the degritting in (b) comprises hydrocycloning the slurry with a hydrocyclone.  
     
     
         43 . The method according to  claim 42 , wherein prior to introducing the slaked lime slurry in (a) into the hydrocyclone, the solids content of the slurry ranges from about 2% to about 25% by weight relative to the total weight of the slurry.  
     
     
         44 . The method according to  claim 42 , wherein the slurry is introduced into the hydrocyclone at a pressure ranging from about 30 psi to about 60 psi.  
     
     
         45 . The method according to  claim 42 , wherein the slurry in the hydrocyclone has a temperature ranging from about 25° C. to about 90° C.  
     
     
         46 . The method according to  claim 42 , wherein the hydrocyclone has a vortex finder and a spigot, and a diameter of the vortex finder ranges from about 0.2 to about 0.4 times a diameter of the spigot.  
     
     
         47 . The method according to  claim 42 , wherein the hydrocyclone has a vortex finder and a spigot, the vortex finder having a diameter ranging from about 8 mm to about 20 mm and the spigot having a diameter ranging from about 3 mm to about 9 mm.  
     
     
         48 . The method according to  claim 42 , wherein the slaked lime is screened prior to hydrocycloning.  
     
     
         49 . The method according to  claim 41 , wherein the slaked lime is screened with a 60 mesh screen.  
     
     
         50 . The method according to  claim 37 , wherein a source of the at least one substrate in (c) is a fiber-containing stream.  
     
     
         51 . The method according to claim , wherein a source of the at least one substrate in (c) is a fines-containing stream.  
     
     
         52 . The method according to  claim 37 , wherein a source of the at least one substrate in (c) is whitewater.  
     
     
         53 . The method according to  claim 37 , wherein a source of the at least one substrate in (c) is a waste stream.  
     
     
         54 . The method according to  claim 37 , wherein prior to (d), the at least one substrate is pre-treated to render it suitable for precipitation.  
     
     
         55 . The method according to  claim 37 , wherein the at least one substrate comprises a white mineral.  
     
     
         56 . The method according to  claim 37 , wherein the at least one substrate comprises calcium carbonate.  
     
     
         57 . The method according to  claim 37 , wherein the at least one substrate comprises kaolin.  
     
     
         58 . The method according to  claim 37 , wherein the at least one substrate comprises TiO 2 .  
     
     
         59 . The method according to  claim 37 , wherein the at least one substrate comprises talc.  
     
     
         60 . The method according to  claim 37 , wherein the precipitating in (d) is effected with carbon dioxide.  
     
     
         61 . The method according to  claim 60 , wherein the precipitation with carbon dioxide addition is terminated when the pH of the slurry is less than about 9.0.  
     
     
         62 . The method according to  claim 61 , wherein the precipitation with carbon dioxide addition is terminated when the pH of the slurry is less than about 7.0.  
     
     
         63 . The method according to  claim 37 , wherein the composition formed after the precipitating in (d) is subjected to at least one bleaching agent.  
     
     
         64 . The method according to  claim 37 , wherein the slurry comprising the composition formed after the precipitating in (d) is dewatered.  
     
     
         65 . The method according to  claim 37 , wherein the slurry comprising the composition formed after the precipitating in (d) is diluted.  
     
     
         66 . A paper comprising a composition made according to the process of  claim 37 .  
     
     
         67 . The paper according to  claim 66 , wherein the paper further comprises at least one ingredient chosen from ground calcium carbonate, kaolin, metakaolin, talc, and calcium sulphate.  
     
     
         68 . The paper according to  claim 66 , wherein the composition contains grit in an amount less than or equal to about 0.5% by weight relative to the total weight of the composition.  
     
     
         69 . The paper according to  claim 68 , wherein the composition contains grit in an amount less than or equal to about 0.3% by weight relative to the total weight of the composition.  
     
     
         70 . The paper according to  claim 69 , wherein the composition contains grit in an amount less than or equal to about 0.2% by weight relative to the total weight of the composition.  
     
     
         71 . The paper according to  claim 70 , wherein the composition contains grit in an amount less than or equal to about 0.1% by weight relative to the total weight of the composition.  
     
     
         72 . The paper according to  claim 71 , wherein the composition contains grit in an amount less than or equal to about 0.05% by weight relative to the total weight of the composition.  
     
     
         73 . The paper according to  claim 72 , wherein the composition contains grit in an amount less than or equal to about 0.01 % by weight relative to the total weight of the composition.  
     
     
         74 . A polymer comprising a composition made according to the process of  claim 37 .  
     
     
         75 . A method of reducing grit in a composition, comprising: 
 (a) providing a slaked lime slurry;    (b) degritting the slaked lime slurry;    (c) combining the degritted slaked lime with at least one substrate; and    (d) precipitating the degritted slaked lime in (c) as calcium carbonate in the presence of the at least one substrate,    wherein the slaked lime slurry in (a) has an amount of grit less than the degritted lime slurry after (b).    
     
     
         76 . The method according to  claim 75 , wherein the degritted slaked lime in (c) is precipitated as calcium carbonate onto the at least one substrate.  
     
     
         77 . The method according to  claim 75 , wherein said at least one substrate is chosen from particulate materials and fibrous materials.  
     
     
         78 . The method according to  claim 75 , wherein slaked lime slurry in (a) has an amount of grit of at least about 10,000 ppm and the degrifted lime slurry after (b) has an amount of grit less than or equal to about 1000 ppm.  
     
     
         79 . The method according to  claim 78 , wherein slaked lime slurry in (a) has an amount of grit of at least about 10,000 ppm and the degritted lime slurry after (b) has an amount of grit less than or equal to about 500 ppm.  
     
     
         80 . The method according to  claim 75 , wherein a source of the at least one substrate in (c) is a fiber-containing stream.  
     
     
         81 . The method according to  claim 75 , wherein a source of the at least one substrate in (c) is a fines-containing stream.  
     
     
         82 . The method according to  claim 75 , wherein a source of the at least one substrate in (c) is whitewater.  
     
     
         83 . The method according to  claim 75 , wherein a source of the at least one substrate in (c) is a waste stream.  
     
     
         84 . A system for producing a composition, comprising: 
 a slaked lime entry point for introducing slaked lime;    at least one degritter for removing grit from the slaked lime;    at least one substrate entry point for introducing at least one substrate; and    at least one reactor for receiving degritted slaked lime from the at least one degritter and at least one substrate from the substrate entry point, and for carbonating the degritted slaked lime, thereby precipitating calcium carbonate onto the at least one substrate to form the composition;    wherein the system produces a composition having grit in an amount less than or equal to about 0.5% by weight relative to the total weight of the composition.    
     
     
         85 . The system according to  claim 84 , wherein said at least one degritter is a hydrocyclone.  
     
     
         86 . The system according to  claim 84 , wherein said at least one degritter comprises a combination of a screen and a hydrocyclone.  
     
     
         87 . The system according to  claim 84 , wherein said at least one degritter is a centrifuge.  
     
     
         88 . The system according to  claim 84 , wherein the at least one substrate comprises fibers.  
     
     
         89 . The system according to  claim 84 , wherein the at least one substrate comprises fines.  
     
     
         90 . The system according to  claim 84 , wherein the at least one substrate is derived from whitewater.  
     
     
         91 . The system according to  claim 84 , wherein the at least one substrate is derived from a waste stream.  
     
     
         92 . The system according to  claim 84 , wherein the system produces a composition having grit in an amount less than or equal to about 0.3% by weight relative to the total weight of the composition.  
     
     
         93 . The system according  claim 92 , wherein the system produces a composition having grit in an amount less than or equal to about 0.2% by weight relative to the total weight of the composition.  
     
     
         94 . The system according to  claim 93 , wherein the system produces a composition having grit in an amount less than or equal to about 0.1% by weight relative to the total weight of the composition.  
     
     
         95 . The system according to  claim 94 , wherein the system produces a composition having grit in an amount less than or equal to about 0.05% by weight relative to the total weight of the composition.  
     
     
         96 . The system according to  claim 95 , wherein the system produces a composition having grit in an amount less than or equal to about 0.01% by weight relative to the total weight of the composition.  
     
     
         97 . A system for producing a composition, comprising: 
 at least one substrate;    at least one source of alkaline earth metal;    at least one hydrocyclone, for degritting the source of alkaline earth metal; and    at least one reactor disposed to receive the at least one substrate and the degrifted alkaline earth metal, and for carbonating the alkaline earth metal to precipitate an alkaline earth metal carbonate in the presence of the at least one substrate;    wherein the system produces a composition having grit in an amount less than or equal to about 0.5% by weight relative to the total weight of the composition.